My cistern is overflowing and leaking out into the back garden (better there than the house!) My husband changed the ball valve and adjusted the screw so the water storage level was as low as possible, and it worked....for about a month! Its getting worse than it used to be, although it stops for about half an hour if you flush the toilet. Its definitely cold water, as I've been splashed by it a few times. Any ideas on what to do to stop it? We are in a very hard water area, could that be affecting the components inside the cistern? If so, any ideas how to help it? Got to get something sorted out soon, our neighbours are not so friendly any more as the water leaking out is splashing on their window and leaves limescale deposits and they are not amused!